Safety device for elevators.



E. s. MATTHEWS. SAFETY DEVICE FOR ELEVATORS.

APPLICATION FILED DEC. 30, 1908.

1,032,340. Patented July 9, 1912.

. 3 SHEETS- SHEET 1.

E. S. MATTHEWS.

SAFETY DEVICE? FOR ELEVATORS.

APPLICATION FILED DEC. 30, 1908.

Patented July 9, 1912.

3 SEEETS-SHEET 2.

COLUMBIA PLANOURAPH 1:0..WA5HIN01'0N, b c.

E. S. MATTHEWS.

SAFETY DEVICE FOR ELEVATORS.

APPLICATION FILED DEC. 30, 1908.

1,032,340. Patented July 9, 1912.

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EDWIN S. MATTHEWS, OF NEW YORK, N. Y., ASSIGNOR TO OTIS ELEVATORCOMPANY, OF JERSEY. CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

SAFETY DEVICE FOR ELEVATORS.

To all whom it may concern:

Be it known that I, EDWIN S. MATTHEWS, a citizen of the United States,residing in New York, in the county of New York and State of New York,have invented a new and useful Improvement in Safety Devices forElevators, of which the following is a specification.

My invention relates to improvements in safety devices for elevators;and has for one of its objects the provision of means for quickly andpowerfully clamping an elevator car to the guides over which it isadapted to travel should the car for any reason exceed a certainpredetermined speed in any direction, the arrangement being such thatthe car is brought to rest before the same has acquired too muchmomentum.

A further object is the provision of a safety device of the guideclamping type, in which the gripping jaws are quickly applied to theguldes with a predetermined pressure and continue to tighten upon themand with increased power until the mo ment-um of the car is overcome andthe latter comes to rest.

Other objects of my invention will appear hereinafter, the novelcombinations of ele ments being pointed out in the appended claims.

A practical embodiment of my invention is represented in theaccompanying drawings forming a part of this specification, in whichlike characters of reference denote corresponding parts in all of thefigures.

Figure 1 is a diagrammatic viewin side elevation of an elevator car. andcertain connected apparatus which may be used in carrying out myinvention; Fig. 2 is a sectional plan view of the safety device; Fig. 3is a transverse section on the line a-a of Fig. 2; Fig. 4 is a sideelevation of Fig. 2; Figs. 5 and 6 are side section and end views,respectively, of a cable clamping device; Fig. 7 is a view inperspective of one of the traveling nuts; Fig. 8 is a view similar toFig. 4, showing a modification; and Fig. 9 is a sectional side View ofFig. 8 upon the line bb looking in the direction of the arrows.

10 designates an elevator car, to the bottom of which my device isattached.

11 is a hoisting cable which is secured to the top of the car andconnected to any desired hoisting apparatus.

Specification of Letters Patent.

Application filed December.30, 1908.

Patented July 9, 1912.

Serial No. 469,933.

12 is a govenor cable connected to run with the car. This governor cableruns under a sheave 20 located near one end of the cars travel. It maybe weighted as at 22, and pawls 21, 21 may be provided, if desired, toengage with ratchets in the sides of the weight 22 to prevent its upwardmove ment. The governor cable 12 runs over another sheave 13 near theother end of the cars travel, which is connected to a governor or speedregulator 14 by suitable gearing 15. The governor 14 is arranged toactuate gripping devices 16, 16 which grip and positively lock thegovernor cable 12 whenever the car exceeds its normal speed. It may beregulated or set to operate at any desired speed, and may be arranged tooperate when the car is running in either direction. The governor cableis yieldingly connected to the car at 17, and is so arranged that whenthe governor cable is stopped and the car continues to move it will pullawayfrom the yielding connection. This will cause the cable 18 which isattached to the governor cable 12 at 61 to be pulled through the pulleys19, 19 and to be unwound from a drum 23 on the'safety device, andthereby impart a rotary motion to the winding drum.

It is sometimes desirable to operate the safety device by hand from thecar, and for this purpose I have provided a ratchet lever in the car, bymeans of which the operator may at any time apply the safety device soas to retard the speed of the car or to bring the latter to a full stop.

I will now refer to the other figures, and describe the clamping orsafety device which is there illustrated.

26 designates a framework of channel beam construction which carries theclamping apparatus and which is preferably secured to the bottom of theelevator car, although under certain conditions it may be locatedelsewhere. Since the various parts of the apparatus shown in Fig. 2 aresymmetrically arranged with respect to a common central line, I willrefer in the description to but one of the similar halves.

29 29 designate a pair of gripping members pivoted to the frame 26 at-30 and provided at one end with clamping jaws adapted to engage adjacentsides of the guide rail 28, but normally out of contact therewith. Theother end of the gripping members 29 forced between the rollers, therebycausing.

the clamping aws to move into engagement with the lateral surfaces ofthe guide rail 28. Normally the clamping jaws should be held wholly outof engagement with said guide rails by means of a spring, such as 33,acting on the gripping members 29, 29.

Rotatably mounted intermediate the fixed supports 42 and 42 is thesafety drum 23, on which the cable 18 (Fig. 1) is wound. If desired,this drum may be grooved as shown to receive said cable, although undercertain conditions the surface of the drum may be cylindrical. In eithercase the cable 18 is wound upon the drum several turns andhas its endsecured thereto. The drum 23 is carried upon the left and right-handscrews 37, 37 which are adapted to rotate with the drum through thespline connection 27. The screws 37 and 37 pass loosely through thesupports 42, 42 and are threaded into traveling nuts 38, 38,respectively. Each of these nuts, such as 38, is provided with guideportions 39, 39 which pass through corresponding slots in the support 42and extend into an annular recess 40 formed in the drum. Between'eachtraveling nut and its corresponding support, a pair of similar wedges,such as 44 and 46, are located. Each of these wedges passes throughslots 43 and 45 formed in the support 42 and the channel beams 26, 26,the slots being of sufficient length to allow for clearance when thewedges are moved into operative position. The faces of the wedgesadjacent the support 42 are flat, while the faces in contact with thenut 38 are tapered or inclined to correspond to the inclined face 41(Fig.v 7) of the nut. The angle of inclination of the engaging faces ofthe wedges and the traveling nut, where one face of each wedge is fiatas shown, should not as a rule exceed four degrees, although in somecases I contemplate using a greater or lesser angle of inclination. Thewedges of each pair are secured at the bottom by a strut47 andthrough-bolt 48, and each pair of'wedges is connected at the top bymeans of bolts 49 to an off-set frame 50. This frame contains a slot 51,in which a cable clamp 53 is arranged to have a longitudinal movementonly. The clamp is shown in detail in Figs. 5 and 6, and comprises abody portion of larger diameter than. that of the slot 51, and having agroove turned in the periphery of the clamp to receive the slot. Theclamp has a tortuous hole through the center, which contains the cable18 and a leaf spring 54. Set-screws 55, 55 bear against the spring 54,and by adjusting said without departing from the Spirit of this screwsthe frictional engagement between the clampand the cable 18 may bevaried to any desired amount. It is evident that only a portion of thepower of the governor cable is utilized to effect the quick motion ofthe slack take-up, and that other methods obviously might be employedfor dividing a certain proportion of the power of the cable between thewedges and the drum invention. In order to insure that all of the wedgeswill be moved simultaneously, I provide. a squaring device comprising ashaft 56 supported in bearings 58, 58 upon the channel beam 26,. saidshaft carrying upon either end a rigidly secured pinion 57 57 arrangedto mesh with corresponding rack teeth 59, 59 cut in the wedges 44 and 44The operation of the apparatus thus de scribed is as follows: As soon asthe elevator car exceeds a certain predetermined speed in eitherdirection, the governor 14 operates to lock the governor cable 12against further movement. As the car continues to move, the cable 18 ispulled between the pulleys 19,19, carrying with it the frame 50 to whichthe wedges are fastened, and

also at the same time causing the drum 23 and screws 37 37 to rotate. Asthe wedges move upwardly (Fig. 2), the traveling nuts 38 and 38,together with the screws 37, 37 are moved outwardly, forcing the wedges31, 31 between the rollers 34, 34 and 34, 34, respectively, therebyclamping the gripping jaws at either end of the safety device upon theirrespective guide rails. As soon as the gripping jaws come intoengagement with the guide rails, the resistance to thefurther movementof the wedges 44, 44, etc. immediately increases until it reaches anamount sufficient to overcome the frictional engagement existing betweenthe cable 18 and the cable clamp 53 which limits the pressure exerted bythe wedges. As soon as this point has been reached, the cable slipsthrough the clamp 53 and continues to rotate the drum, the clamp 53traveling in the slot 51 as the cable unwinds. The screws 37, 37 drivenby the drum through the spline 27 will continue to rotate in the nuts38, 38 and move bodily outwardly, thereby forcing the wedges 31, 31between the rollers 34, 34 and causing thegripping aws to clamp theguide rails with great power. In this manner the moving elevator car isquickly and smoothly brought to rest.

In order to reset the safety device after the same has operated, a barmay be inserted in the holes 66 in the periphery of the safety drum- 23,and the latter, together with the screws 37, 37, will be rotatedbackward. In this manner the gripping jaws will release their hold uponthe guide rails, 13o

and the wedges 44, 46, etc., will be pulled back into normal position byreason of the frictional engagement existing between the wedges and thecable 18 at the clamp 53. The yielding connection 17 is again placed innormal position and the safety device is once more restored to normalconditions. WVhen the safety device operates with an upwardly movingcar, a portion of the cable 67 will be unwound from the drum 64, whilewith a downwardly moving car the cable 67 will be slacked. In the firstinstance it would be necessary when resetting the safety again to windthe cable 67 upon the drum, while in the second instance the slack inthis cable will be automatically taken up.

Referring to the modification shown in Figs. 8 and 9, 72, 72 designate apair of similar clamping members or dogs which are secured upon shafts74, 74, arranged to rotate in bearings 73, 73 carried by the frame 50.Upon each end of the shafts 74, 74 are secured lever arms, such as 76, 76, and between adjacent lever arms is a tension spring 77 so arrangedthat its tension may be readily adjusted to any-desired degree. Betweenthe dogs 72, 72 is located the cable 18, to which is rigidly attached acable bob 53. This bob 53 when in normal position is located just belowthe dogs 72, 72 and in contact therewith. Fixed stops 79, 79 arearranged upon the bearings 7 3, 73 which cooperate with correspondingdetents 79, 79 whose function is to limit the movement of the dogs 72,72 toward each other effected by the action of the springs 77, 77. Theoperation of this device is as follows: As soon as the safety device isset into opera tion, motion is imparted to the cable 18 and bob 53affixed thereto, and the latter tends to force apart or rotate the dogs72, 72.

Since the dogs are spring pressed, in order to pull the bob through thedogs against the action of the springs a certain resistance must beovercome, and the magnitude of this resistance is determined largely bythe amount of tension in the springs. It is readily seen that as the bobmoves upwardly (Fig. 9) it carries with it the dogs 72, 72, togetherwith the frame 50 and connected wedges 44, 46, etc. In this manner thewedges operate to quickly take up all lost motion and backlash in thesafety device mechanism and to set the clamping jaws upon the guiderails as before pointed out.

As soon as the wedges meet with a certain resistance to their furthermovement, the dogs 72, 72 connected thereto are forcibly opened by thebob 53 as the latter continues to move upwardly. As soon as the bob hasmoved out of engagement with the dogs 7 2, 72 the latter are moved backinto original position against the stops 7 9, 7 9 by means of thesprings 77. It is readily seen that as soon as the bob has been pulledthrough the dogs and the latter have returned to original posit-ion, thecable 18 is no longer retarded in its movement by the dogs and theirconnected parts, and the tension in the same is reduced to an amountjust sufficient to continue to rotate the drum on the safety device. Inthis manner the strain upon the cable 18, as well as that upon thegovernor cable 12, is reduced to a minimum. It will be noticed upon aninspection of Fig. 9 that the bob 53 is tapered at either end, the taperat the upper end being considerably less than that at the bottom. Thetaper at the top of the bob, together with the inclination of the lowersurfaces of the dogs and the tension of the springs 77, 77, determinesthe amount of frictional engagement existing between the cable 18 andthe dogs, and by varying any one of these cooperating elements, such asthe tension of the springs 77 77 the upward pull upon the wedges may beregulated to any desired amount. The taper upon the bottom of the bob isgradual so that when resetting the safety device by hand the bob willreadily force the dogs apart and come to its original position withminimum effort upon the part of the operator. Whereas it is onlynecessary to employ a single spring 77 to actuate the dogs 72, 72, Iprefer to use two springs so that in case one should become broken thedevice would still be effective.

In safety devices of this general character it is customary to cause thegripping jaws first to move quickly into position against the lateralfaces of the guide rails by means of springs, cams, high pitch screws,or similar devices, after which a low pitch screw is called intooperation to gradually tighten the jaws upon the rails. Such methods areopen to the objection that they all operate on similar principles; thatis, they require two mechanisms for operating the gripping jaws, onemechanism being arranged to first move the jaws int-o engaging positionon the rails with a certain pressure, after which the other mechanism iscalled into operation to further tighten the aws upon the rails untilthe car finally comes to rest. The operation of each of these mechanismsmay be independent of each other or not, as the case may be; in eithercase the failure of one to operate at the proper time will seriouslyaffect the operation of the safety device as a whole. In a safety deviceembodying my invention, the quick acting means for bringing the grippingaws into engagament with the guide rails, and the slower and morepowerful means for tightening the aws upon the rails, are set intooperation simultaneously the moment the governor grips the governorcable, and the safety drum 23 starts to rotate. Since the cable 18 isunwound from the drum 23 at the same speed that the elevator car ismoving, the wedges 44, 46, etc.,

will be pulled upwardly (Figs. 2 and 3) by means of the frictionconnect-ion between said cable and the clamp 53 in a very short space oftime, depending upon the pitch of the inclined faces of the wedges. Thispitch, as before stated, should not be too steep, for the reason thatthere would be danger of the wedges being forced backward against theopposing frictional pull of the cable clamp 53, as the thrust of thetraveling nuts against these wedges will greatly increase as therotating screws 37 37 force the gripping jaws against the rails withgreat power. Since the wedges 4A, 46, etc., are operated by reason ofthe friction existing bet-ween the cable 18 and clamp 53, and since thisfriction may be adjusted or regulated to any desired amount by means ofthe screws 55, the apparatus may be so adjusted that the wedges willmerely bring the gripping jaws into position against the rails, or, ifso desired, this friction may be increased so that the wedges will setthe jaws with a certain predetermined pressure on the rails. As soon asthe wedges have performed their function, the screws 37, 37 furtherincrease this pressure until sufiicient friction exists between therails and the gripping jaws to stop and hold the car against furthermovement. Since the simultaneous operation of the wedges 4A, 46, etc.,and the screws 37, 37, in bringing the jaws into engagement with therails takes place very quickly, the

pitch of the screws 37, 37' may be correspondingly low, and thus thestrain upon the cable 18 will be comparatively small, while at the sametime the jaws will be tightened upon the rails with sufficient power tostop the car before the same has acquired too much momentum.

The means for operating the safety de vice from the car comprises acable drum 64 located upon the outside of the car, which contains acable 67. This cable is wound about the drum a number of turns and hasone end connected thereto. The other end of the cable leads up oversuitable guide pulleys 68 and is connected at 61 to the governor cable12 and cable 18. The drum 64 is rigidly connected to a toothed wheel 63which is arranged to cooperate with a latch 70 carried upon the lever60. This lever is preferably arranged in close proximity to the caroperating lever 65 so as to be within convenient reach of the operator.The latch 7 0 is normally held out of engagement with the toothed wheel63 by means of a spring 69 and the same may be placed into engagementwith the toothed wheel by means of the hand lever 62. Under normalconditions the drum 6 1 is free to rotate; thus the manually operablemeans does not interfere in any way with the proper operation of theautomatic means for applying the safety device. In order to operate thesafety device from the car, the operator grasps the levers 60 and 62,and by so doing forces the latch 70 into engagement with the toothedwheel 68 and thus places the lever 60 into operative connection with thedrum 64. Upon pulling the lever to the right, the drum 64: is rotated ina clock-wise direction, thereby winding up the cable 67. Since thiscable is operatively connected to the cable 18, the latter is pulledthrough the pulleys 19, thereby effecting theoperation of the safetydevice as before described in connection with the automatic operationeffected by the speed governor. The drum 6% may be rotated any desiredamount by rocking the lever 60 back and forth, the latch 70 beingdisengaged from the toothed wheel 63 when the lever 60 is moved in aleft-hand direction by relieving the pressure upon the leplies a simpleand efficient apparatus for automatically stopping an elevator car whosespeed has exceeded a certain predetermined limit in as short a space oftime as is prac tical. The interval of time required to move thegripping jaws from normal position into a position against the guiderails being so short that for all practical purposes the operation issubstantially instantaneous, a restraining influence is brought to bearupon the moving elevator car before the same has had time to move morethan two or three inches. The act-ion of the right and leftscrews infurther forcing the jaws upon the guide rails is much slower, withcorrespondingly greater power. In this manner the safety device promptlygets into action the moment the governor acts, and by the gradualapplication of increasing holding power produces a sure and gradualstop. I

While I have shown a preferred construction of my device, I desire notto be limited to the precise arrangement of parts herein disclosed,since it is obvious that those skilled in the art could readily makevarious changes in details of construction without departing from thespirit and scope of my invention.

What I claim as new and desire to have protected by Letters Patent ofthe United States is:

1. In an elevator safety device, the combination of a car, guides overwhich the car travels, clamping jaws carried by the car and arranged toengage the guides, means comprising wedges for quickly operating theclamping jaws, additional means for slowly operating said clamping jaws,and means for effecting the simultaneousaction of both of said operatingmeans. W

2. In an elevator; safety device,fthecombination of a car, guide railstherefor, clamps carried by the car and adapted to engage said guiderails, frictional means for operating the clamps, positive means foroperating the clamps, and means for effecting the simultaneous operationof both of said operating means.

3. In a safety device for elevators, the combination of guide rails,gripping members adapted to engage said guide rails, wedges for movingthe gripping members quickly into operative position, screws fortightening said gripping members slowly upon the guide rails, means foreflecting a simultaneous operation of said wedges and screws, and fordiscontinuing the movement of said wedges when the gripping members meetwith resistance.

4-. in a safety device for elevators, the combination of a car, guiderails therefor, clamps carried upon said car, a device for operatingsaid clamps, wedges for effecting the operation of said device wherebysaid clamps will engage said guide rails with a predetermined pressure,and screws for further increasing this pressure.

5. In an elevator safety device, the combination of a car, guide railstherefor, a clamping device, friction operated means for actuating saidclamping device positively operated means for actuating said clampingdevice, and means operative upon excessive car speed for simultaneouslyefiecting the operation of both of said clamp actuating means.

6. The combination with an elevator car, of a clamping device comprisinggripping jaws, right and left threaded screws associated with said jaws,means for rotating both screws, a nut threaded upon each of the screws,wedges arranged bodily to move each nut, and means for effecting asimultaneous movement of said wedges and a ro tat-ion of said screws.

7. The combination with an elevator car,

of a clamping device therefor, right and left screws associated withsaid clamping device, a nut threaded upon each of said screws, wedgesarranged bodily to move each nut, a governor, and means associated withsaid governor for effecting simultaneously a movement of the wedges anda rotation of said screws.

8. The combination with an elevator car,

of a clamping device therefor, right and left screws associated withsaid clamping device, nuts threaded upon each of the screws, wedgesco-acting with said nuts, means for simultaneously effecting alongitudinal and rotary motion to said screws, and means for limitingsaid longitudinal movement when the clamping device meets withresistance.

9. In an elevator safety device, the combination of a car, a clampingdevice carried by said car, frictional means for operating said clampingdevice, positive means for operating said clamping device, andindependent automatic and manual means for effect ing the simultaneousoperation of both of W. H. BRADY, Erma L. Aus'rnnn.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

' Washington, 1). 0.

